Radio Frequency Identification (RFID) systems have become increasingly prevalent and can be used to identify people as well as objects. An RFID system may be configured to include at least one RFID reader (also referred to herein as reader) and one or more RFID tags (also referred to herein as tags). The RFID reader transmits radio frequency (RF) signals and receives RF signals from one or more tags within a certain range. It should be noted that actual coverage areas within which readers transmit and receive RF signals are often not uniform and depend on many factors, including but not limited to, an antenna configuration of each reader, the RF characteristics of the area around the reader (e.g. empty space vs. metal obstructions), or the transmit power of each reader. RFID tags are typically compact and are attachable to objects.
RFID tags are configured to include an integrated circuit for storing and processing information, modulating and demodulating RF signals, and performing other specialized functions. RFID tags may include an antenna in communication with the integrated circuit, wherein the antenna is used for transmitting RF signals to and receiving RF signals from the RFID reader. An RFID tag is usually tuned to a particular frequency band.
In some implementations, RFID systems are deployed as part of an inventory management system. To maintain an accurate, up-to-date inventory of items for sale, as part of the inventory management system, retail establishments may deploy separate interconnected systems, such as an automated inventory tracking system for tracking the presence and locations of items in the establishment and a point of sale system for monitoring which items are sold. The presence and locations of items in the establishment may be tracked by affixing an RFID tag on each item for which automated inventory tracking is desired. The automated inventory tracking system may include RFID readers powered with relatively small batteries. These readers may be distributed throughout the establishment to provide RF coverage for areas where tagged items may be located. Each reader periodically polls or interrogates the RFID tags within its coverage area, i.e. each reader sends RF signals to and receives RF signals from tags within its coverage area. After polling the tags for a predefined length of time (interrogation length), the readers may send a list of read or retrieved tag identifiers (IDs) to a single central server via, for example, Wireless Fidelity (Wi-Fi). Based on data aggregated from one or more polls and/or from one or more readers, the server may maintain key measurements for items in the inventory. For example, the server may maintain measurements about which items are present at a predefined location in the establishment. The server is capable of directing polling intervals, i.e. directing how long each reader in the establishment is to wait before performing a subsequent poll.
Allowing all readers in the establishment to conduct frequent polls provides for timely notifications of changes for items being tracked. For example, when all readers in the establishment conduct frequent polls, the server is able to quickly identify when a tracked tagged item has been moved from one location to another. The server may also increase the interrogation length (the length of time the reader can send RF signals to and receive RF signals from tags) or increase the reader's transmit power in an attempt to receive RF signals from more tags. However, when the server instructs the reader to conduct frequent polls, increase the interrogation length and/or increase its transmit power, the reader also increases usage of its battery power.
To minimize consumption of the reader's battery power, one approach allows for power savings by shutting off the readers during times when the establishment is closed. Using this approach, the reader may be manually or automatically shut down when the establishment is closed to minimize battery power consumption. However, this approach does not provide an avenue for minimizing battery power consumption while the establishment is open and the system is expected to produce useable results.
Another approach to minimizing battery power consumption reduces wired or wireless reader to server communications. In this approach, only the difference between results of a most recent poll and a poll immediately prior to the most recent poll is sent from the reader to the server. It is noted, however, that communications between the reader and tags use a larger portion of the reader's total battery power than the communications between the reader and the server. Therefore, reduction of wired or wireless reader to server communications minimally affects the overall battery power consumption.
Another approach allows for minimizing the battery power consumption by measuring inventory change or volatility within the automated inventory tracking system and making adjustments to polling parameters, such as the polling frequency or interrogation length, based upon the measurements. It is noted, however, that this approach does not take into account inventory change or volatility measurements made by other systems, such as point of sale systems, within the broader inventory management system.
Accordingly, a method is needed for optimizing power consumption in the RFID radio by adjusting polling parameters based on information obtained from separate systems within the inventory management system.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.